Process for compounding and vulcanizing rubber and products obtained therefrom



Patented Feb. 12, 1920.

UNITED. STATES. PATENT OFFICE.

SIDNEY M. CAJJWELL, F IZEONIA, NEW JERSEY, ASSIGNOR TO THE NAUGATUCK CHEMICAL COMPANY, OF NAUGATUCK, CONNECTICUT, A CORPORATION OF CON- :uncrrrcur.

PROCESS FOR COHPOUNDING- AND VULCANIZING RUBBER AND PRODUCTS OBTAINED THEBEFROM.

' No Drawing. Application alea December 17, 1923, Serial No. 681,066. Renewed July 12, 1928.

tion is to provide a simple process for introducing one or two vulcanizing ingredients which form art of an active vulcanlzmg combination, 1nto sheet rubber or otherwise previously shaped rubber while avoiding prevulcanization thereof. Another object of the invention is to provide a series of useful products from such process having desirable physical characteristics.

It has been found in accordance with the present invention that vulcanizatlon at ordinary temperatures, approiiimately 70 may be carried out when the four ingredients, M in combination, where M represents zinc or other metal defined hereinafter, an amine. a material comprising sulphur and a material comprising carbon disulphide are presout. At temperatures above the ordinary temperature, say 212 F. or 240-286 F. (the temperature of normal hot vulcanization), or above, vulcanization occurs at an increased rate.

The invention accordingly comprises a process for introducing materials into rubber which includes combining two of the four vulcanizing ingredients, namely an amine, a material containing carbon disul- 40 phide, a metal M in combination, and sulphur, with rubber, and substantially without changing the form of the combination introducing the remaining vulcaniziug ingrodients from a medium other than rubber. It

also includes combining three of the four vulcanizing ingredients mentioned above with rubber and substantially without changing the shape of the combination introducing the remaining vulcanizing ingredient from solution. It also includes products resulting from such processes.

In carrying out the invention in its preferred form, the following procedure. is employed: 100 parts of pale crepe rubber, 10 parts of zinc oxide, and 3 parts of sulphur, are combined by milling in the ordinary manner. The material is calendered to form a thin sheet, say .010 inch thick and this sheet is painted with carbon disulphide and dibenzylamine solutions, the carbon disulphlde being employed in the form of a 5% benzol solution, the dibenzylamine being employed in the form of a 3.2% benzol solution. The carbon disulphide and dibcnzylamine may be applied separately or combined, each or both solutions being applied at. three .minute intervals four times. After standing over night the sheet is heated to 212 C. in open air for 1 hr. at the end-of which time vulcanization is accomplished.

Other procedures falling within the invention are as follows: 10 parts of zinc oxide, 3.2 parts of dibenzylamine are combined with 100 parts of rubber by milling. A thin film of this material is subjected to 10% benzol solution of oxy normal butylthiocarbonic acid disulphide by painting four times at three minuteintervals, and the material is vulcanized asgiven in the preferred embodiment above. OXy normal butylthiocarbonic acid disulphide comprises carbon disulphide and sulphur which with zinc oxide and dibenzylamine make up the four ingredi ents forvulcanization. Instead of oxy normal butylthiocarbonic acid disulphide a mixture of carbon disulphide 20% and sulphur 5% in benzol may be painted upon the sheet and vulcanization carried out in the same manner as in the preferred example.

As another example 4 parts zincbutyl Xanthogenate which provides carbon disulphide and zinc in combination as two of the four ingredients are milled with 100 parts rubber, and a thin sheet'.0l0 inch in thickness is treated With a benzol solution containing dibenzylan'linc 3.29;; and sulphur 1%, vulcanization being accomplished as in the other examples.

Or 10 parts of oxy normal butyl thiocarbonic acid disulphide, providing-carbon di sulphide and sulphur of the four ingredients is combined with 100 parts rubber by milling, and a thin sheet .010 inch thickness is subjectcd to a benzol solution of zinc stearate 3% and dibenzylamine 3.2%.

As another example 3 parts of sulphur and 3.2 parts of dibenzylamine are combined with 100 parts of rubber by milling, and a thm sheet as heretofore is subjected to a benzol solution containing 4% of zinc butyl xanthogenate, which furnishes zinc in combination and carbon disulphide of .the four ingredients. Vulcanization is accomplished as in the other examples. Instead of treating crude rubber,

' latex may be employed. The uncoagulated latex is mixed with an amount of zinc oxide corresponding to 10 parts on 100 parts of dried rubber and with an amount of sulphur corresponding to 3 parts on 100 parts of dried rubber. The latex is dried in a sheet, for instance, and the dried latex-rubber sul hur mixture is painted with dibenzylamine w ich is absorbed and permeates throughout the rubber mass. Subsequently it is painted with carbon disulphide which in turn is absorbed,

permeates throughout the rubber mass and reacts with the chemicals alread present, and causes vulcanization which will occur in the course of a weelc at ordinary temperatures,or upon heating for two hours at 212 F.

The products resulting from the above processes have desirable physical characteristics including high tensile strength and go (1 resistance to ageing.

stead of combining twoingredients with rubber and then introducing two 'othersfrom a medium other than rubber as indicated above, three ingredients may be combined with the rubber and other vulcanizing inedients may be introduced by absorption.

om a solution.

ments of this phaseof theinvention:

100 parts of rubber are combined with 4 parts of zinc butyl xanthogenate. (including carbon disul hideand zinc in combination) and 2 parts ibenzylamine. A 'thin film .010-

inchin thickness for ex'ampleis treated with a solutionof sulphur in carbon disulphide until approximately 1 part. ofsulphur is absorbed y the rubber.

As another example 2 parts of dibenzylamine and 5 partsof, oxy'normal butyl thioa thin film is treated with a 3% solution of diof aniline is absorbed.

benzylamine in-benzol parts ofdibenzylamine are absorbed. I I As an alternative instead of treating the above composition with dibenzylamine in "solution, it may be treated with anaqueousro'ximately .1 part.

e rubber treated aniline solution until ap The followingjprocesses represent embodi by any of the preceding procedures is vul- Jan. 2, 1923, 1,440,963, Jan. 2, 1923, 1,440,964,

Jan. 2, 1923 and copending applications Sr. Nos. 548,828, 548,829, 548,831, filed 'April 1, 1922, which have become Patents Nos. 1,532,226, 1,532,227 and 1,510,652, respectively. Sulphur may be employed as such or in a compound adapted to transfersulphur from itself to rubber under vulcanizing conditions as set forth in copending applications Sr. N 0. 359,807, filed Feb. 19, 1920 and Sr. N 0. 528,278, filed Jan. 10, 1922, now Patent No. 1,532,225. Various amines may be used and in general the observations set forth in connection with amines as mentioned in the patcuts and applications above areapplicable in connection with the present processes. Instead of using 'zinc various metals set' forth in the patents mentioned may be employed under the conditions therein stated. Briefly stated'these metals which I have designated as M are as follows :-zinc, mercur preferably in the mercuric state, lead, pre erably in the plumbous state, cadmium, copper, preferably in the cupric state, arsenic, preferably in the arsenous state, manganese, preferably --m the manganous state.

The processes of the present invention are simple economical ones. By eliminating the introduction of all of the ingredients by milling, danger of prevulcanization is avoided.

Materials which are ordinarily classed under the term rubber including balata, gutta percha, synthetic rubber, may be similarly employed in carryin out the invention, and it is intended to inc ude such substances by the term rubber as herein employed.

The expression carbon d1sulphide containin material as used herein is intended to inc ude the substance carbon disulphide itself.

As many apparently widely different embodiments of this invention maybe made without departing from the spirit thereof, it will be herein set forth ap nded claims.

' avmg thus described my invention, I and desire .to protect by en 1s:

except as indicated in the understood that I do not intend to lumt myself to the specific embodiments what Pat-;

1', Api-ocemfor material 180,

LMLKMQ than one of the four vulcanizing ingredients,

viz z-dibenzylamine, a material containing carbon disulphide, zinc in combination, and

sulphur, into rubber, and substantiall without changing the form of the combination introducing the remainder of the vulcanizing ingredients from solution, the dibenzylamine and carbon dimlphide b'eing always. separately introduced.

2. The method of producing vulcanized rubber, which comprises completin at least theheavy milling and mixing of t e rubber compound, and thereafter first difiusing into the rubber compound one com onent of an accelerator, and then difiusing mto the rubber compound the other component of said accelerator.

3, The method of producing a vulcanized rubber article, which comprises completing the heavy milling and mixin of the rubber compound and at least artia y forming the article, and thereafter rst difiusing into the at least partially formed article one com onent of an accelerator, and then difiusln into said article the other component of sai accelerator.

4. The method of producing vulcanized rubber, which comprises completing at least the. heavy millin and mixing of the rubber compound, and t ereafter first difiusing into the rubber compound one component of an accelerator, and then difiusing into the rubber compound the other component of said accelerator, at least one of said components being applied 'n liquid form.

Signed at ew York, New York, this 11th day of December, 1923.

SIDNEY M. oAnwELL. 

